1. Field of the Invention
The present invention relates to an apparatus for detecting an end portion of a recording medium for applying to a printer which prints a predetermined subject on a roll of continuous paper, and more particularly, to an apparatus for detecting an end portion of a recording medium for applying to a printer which performs a print operation with a predetermined maximum print size.
2. Description of Related Art
Printers which print a predetermined subject on a roll of continuous paper then cut the continuous paper in a position corresponding to a print size are known.
The above printers include a printer having a hopper to accommodate the continuous paper. As the form of accommodation of continuous paper in the hopper, the printers are briefly classified into printer having a hopper with a support shaft to support the center of the continuous paper and a printer having a hopper without such support shaft.
For example, for a print operation with a predetermined print size of e.g. securities or ATM statement information, various printers capable of detecting a remaining amount of unprinted continuous paper lest the continuous paper become short during print operation are known.
In a case where a remaining amount of continuous paper is detected in a printer having a hopper without support shaft, there is a printer applied an apparatus for detecting an end portion of a recording medium for detecting a rear end of the continuous paper on a guide passage from the hopper to a print unit, or there is a printer applied an apparatus for detecting an end portion of a recording medium for detecting a near end of the continuous paper in correspondence with an outer diameter.
However, to prevent shortage of continuous paper during a print operation by using the former apparatus for detecting an end portion of a recording medium, as it is necessary to ensure a passage length equal to or longer than a predetermined maximum print size as a length from a rear-end detection position to the print unit on the guide passage, the printer increases in size.
Further, in a case where the latter apparatus for detecting an end portion of a recording medium is used, as only the near end of the continuous paper is detected, the continuous paper cannot be effectively used to the rear end, thus the continuous paper is wasted by the unprinted and discarded amount.
In some of the printers having a hopper with support shaft, an encoder to the support shaft, and the remaining amount of continuous paper is detected by detecting rotation of the encoder in accordance with rotation of the support shaft. Since the encoder is attached to the support shaft and a mechanism to detect the rotation of the encoder is provided, the structure of the printer is complicated.
Further, in some printers, a roller for rotation detection is provided in contact with an outer peripheral surface of the continuous paper, and an encoder is attached to the roller, such that the remaining amount of the continuous paper is detected by detecting rotation of the encoder in accordance with rotation of the roller. However, as in the case of the above-described art, since the encoder is attached to the roller and a mechanism to detect the rotation of the encoder is provided, the structure of the printer is complicated.